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Статті в журналах з теми "Stability analyse"
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Carotenuto, L., P. Muraca, and G. Franzè. "Computational method to analyse the stability of interval matrices." IEE Proceedings - Control Theory and Applications 151, no. 6 (November 1, 2004): 669–74. http://dx.doi.org/10.1049/ip-cta:20040907.
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Chen, Wei, Dongbai Li, Ting Ma, Helin Fu, and Yanpeng Du. "Stability Analysis of a Slope considering Two Reinforcement Processes." Geofluids 2020 (November 4, 2020): 1–13. http://dx.doi.org/10.1155/2020/8828747.
Повний текст джерелаАнотація:
The strength reduction method embedded in a distinct element code was used to analyse the stability of a slope in a coal mining area that had been reinforced twice, primarily with pile and retaining wall, followed by porous steel-tube bored grouting. For the primary reinforcement, the factor of safety was calculated, slip surface and failure mechanism were determined, and the damage phenomenon of primary reinforcement was analysed in detail. Failure time of slope without further strengthening was predicted by applying a new quantitative method based on monitoring displacement data. The slope instability at the primary reinforced stage was verified by these analyses. For the second reinforcement, the effect was evaluated by combining the new factor of safety and the final monitoring data, which validates the slope stability. Especially, variations of displacement and factor of safety due to water influence are analysed. Through this procedure, a systemic method for the slope safety evaluation and assurance is presented for engineering practice reference.
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Harfash, Akil J., and Huda A. Challoob. "Nonhomogeneous porosity and thermal diffusivity effects on stability and instability of double-diffusive convection in a porous medium layer: Brinkman Model." Nonlinear Engineering 8, no. 1 (January 28, 2019): 293–302. http://dx.doi.org/10.1515/nleng-2018-2001.
Повний текст джерелаАнотація:
AbstractA model for double-diffusive convection in anisotropic and inhomogeneous porous media has been analysed. In particular, the effect of variable permeability and thermal diffusivity has been studied using the Brinkman model. Moreover, we analyse the effect of slip boundary conditions on the stability of the model. Due to numerous applications in micro-electro-mechanical-systems (MEMS) and other microfluidic devices, such a study is essential to have. Both linear instability analysis and nonlinear stability analysis are employed. We accurately analyse when stability and instability will commence and determine the critical Rayleigh number as a function of the slip coefficient.
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Borges, José. "Vacuum preloading and PVDs in soft soils beneath embankments: 3D coupled analysis incorporating overall stability study." Soils and Rocks 45, no. 3 (July 9, 2022): 1–17. http://dx.doi.org/10.28927/sr.2022.072821.
Повний текст джерелаАнотація:
Although embankments on soft soils with prefabricated vertical drains (PVDs) under vacuum preloading have been widely studied, there is a lack of studies in the literature in which overall stability is analysed through three-dimensional (3D) mechanical-hydraulic coupled modelling. In order to contribute to overcome such deficiency, this paper presents 3D numerical analyses of an embankment on soft soils incorporating PVDs and vacuum preloading. A finite element code, which includes 3D fully coupled analysis, is used and a method for overall stability study – which uses the 3D numerical results obtained with the finite element code – is presented and applied. A parametric study is performed in order to analyse the influence of the magnitude of the vacuum preload and the staged construction of the embankment (time of vacuum application before completion of the embankment). Overall stability, excess pore pressures, settlements, horizontal displacements and stress levels are analysed.
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Sadrinata, Fajar Fairuzy, and Lina Nugraha Rani. "ANALISIS PERBANDINGAN PENGARUH VARIABEL MAKRO EKONOMI TERHADAP STABILITAS BANK SYARIAH DAN BANK KONVENSIONAL DI INDONESIA PERIODE TAHUN 2010-2017." Jurnal Ekonomi Syariah Teori dan Terapan 6, no. 10 (January 18, 2020): 2095. http://dx.doi.org/10.20473/vol6iss201910pp2095-2109.
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The research aims to identify and analyze the partial and simultaneous influence of macroeconomic variables consisting of inflation, GDP, balance of payments, and BI interest rates on the stability of Sharia banks and conventional banks in Indonesia. The research also aims to analyse the differences in macroeconomic variables to influence the stability of banking between sharia banks and conventional banks in Indonesia. The research was based on comparisons of the influence of stability between sharia banks and conventional banks on the macroeconomic variables investigated. The population in this research is sharia Bank and conventional Bank in Indonesia issued by OJK, sharia Bank statistics and conventional Bank. The analytical techniques used are statistical analyses. The analysis of data in this study uses two phases, namely descriptive statistics and inferential statistics.Keywords: inflation, GDP, payment balance, BI interest rates
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Glibowski, Paweł, Michał Skrzypek, Magdalena Ćwiklińska, Monika Drozd, and Aleksandra Kowalska. "Chemical stability of fructans in apple beverages and their influence on chronic constipation." Food & Function 11, no. 5 (2020): 3860–66. http://dx.doi.org/10.1039/c9fo02596k.
Повний текст джерелаАнотація:
The aim of this study was to analyse the content of reducing sugars in beverages obtained on the basis of apple juice with the addition of fructans. Moreover, the effect of consumption of this prebiotic beverage on the constipation was analysed.
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Hui, Jing, Jian-Hua Pang, and Dong-Rong Lin. "Mathematical Analysis of an Epidemic-Species Hybrid Dynamical System." Mathematical Problems in Engineering 2014 (2014): 1–11. http://dx.doi.org/10.1155/2014/810312.
Повний текст джерелаАнотація:
We consider an epidemic-species hybrid dynamical system. The disease is spread among the prey only and the infected prey can reproduce virus. The predator only eats the infected prey. Mathematical analyses are given for the system with regard to the existence of equilibria, local stability, Hopf bifurcation, and the orbital stability of the Hopf bifurcating limit cycle. We further analyse the system under impulsive releasing of virus and predator.
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Brown, K. J., D. Daners, and J. López-Gómez. "Change of stability for Schrödinger semigroups." Proceedings of the Royal Society of Edinburgh: Section A Mathematics 125, no. 4 (1995): 827–46. http://dx.doi.org/10.1017/s0308210500030389.
Повний текст джерелаАнотація:
In this paper we analyse the change of stability of Schrödinger semigroups with indefinite potentials when a coupling parameter varies. Generically, the change of stability takes place at a principal eigenvalue associated with the problem. The uniqueness of the principal eigenvalue is shown for several classes of potentials.
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Kordialik-Bogacka, E., and N. Antczak. "Prediction of beer foam stability from malt components." Czech Journal of Food Sciences 29, No. 3 (May 13, 2011): 243–49. http://dx.doi.org/10.17221/225/2010-cjfs.
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Industrial unhopped worts produced from different batches of commercial malt were taken to analyse the contents of compounds related to beer foam stability, such as polypeptides, polyphenols, and β-glucan. Kolbach index of malts was also determined. Foam stability of beers produced from these wort batches was measured and the relationship between the foam stability and malt components was sought. The findings showed that the great variation in total and hydrophobic polypeptides as well as β-glucan contents among malt batches did not substantially influence the beer foam stability. None of the studied malt parameters correlated highly with the foam stability. The results showed that it is difficult to predict the foam performance relying on the polypeptides, β-glucan, or polyphenol contents in malt. It seems that the scope for the beer foam stability improvement by the malt selection is not considerable.
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Song, Hai Feng, and Wei Wei Yang. "Vehicle Stability Analyse with Electronic Power Steering Based on Yaw Rate Feedback." Applied Mechanics and Materials 397-400 (September 2013): 1351–56. http://dx.doi.org/10.4028/www.scientific.net/amm.397-400.1351.
Повний текст джерелаАнотація:
A control method is proposed to improve vehicle yaw stability by the integrated control of yaw moment control. The control strategy using feedback compensator is proposed, which produces direct yaw moment and front steering angle to control yaw rate, by actively controlling the front steering angle, the integrated control system makes the performance of the actual vehicle model follow that of an ideal vehicle model. A experiment is performed at different conditions, the results showed the presented method can effectively control the yaw rate, and at the same time lighten the burden of the driver. Key words: EPS; Yaw rate feedback; Vehicle stability
Дисертації з теми "Stability analyse"
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Maatar, Dhouha. "Analyse des signaux stabilométriques et de la stabilité chez l’Homme : application à la biométrie." Thesis, Paris Est, 2013. http://www.theses.fr/2013PEST1161/document.
Повний текст джерелаАнотація:
La biométrie se réfère à la reconnaissance automatique des individus. Elle est basée sur leurs caractéristiques physiologiques et/ou comportementales. Le contrôle postural, bien que soit une caractéristique comportementale de l'Homme, n'a pas été bien développée dans le domaine de la biométrie. Le travail mené dans cette thèse repose sur l'analyse des signaux stabilométriques et l'application à la biométrie. Dans un premier volet, une étude de l'information posturale, en particulier le signal stabilométrique, est effectuée à travers des méthodes d'analyses classiques à savoir et l'analyse spatio-temporelle, spectrale et stochastique et à travers aussi deux méthodes de décomposition : la décomposition appelée analyse en composantes principales (ACP) et la décomposition en ondelettes. La méthode ACP, basée sur le modèle additif, permet de décomposer le signal en trois composantes: un signal de tendance, un signal d'excursion et un signal de tremblements. La méthode de décomposition en ondelettes permet de décomposer le signal en trois niveaux de signaux de détail et trois niveaux de signaux d'approximation. Suite à l'étude de la stabilité posturale, l'analyse spectrale et l'analyse de la phase des différentes composantes issues de la ACP et de la décomposition en ondelettes, la comparaison de ces deux méthodes conclut que la méthode ACP est plus appropriée que la décomposition en ondelettes pour analyser le stabilogramme. A partir des méthodes de décomposition et des méthodes d'analyses classiques, des paramètres sont extraits afin d'étudier l'effet de différents facteurs sur la stabilité posturale et sur le déplacement du centre de masse. Ces facteurs sont la vision, la direction, la proprioception, l'âge, le genre, la taille et le poids. Un deuxième volet de ce travail est consacré à l'application biométrique, à partir des paramètres extraits et suite à une analyse statistique ANOVA, ceux qui sont les plus discriminatifs sont utilisés pour identifier des sujets et les classer selon leur âge, genre, poids et taille. Cette application biométrique est effectuée par trois méthodes de classification à savoir, K-ppv, ADL et SVM. Les applications biométriques aboutissent à des taux de reconnaissance respectables dépassant 80%. De ce fait, il est à déduire que l'analyse du contrôle postural est prometteuse dans le domaine de la biométrieBiometrics refers to automatic recognition of individuals. It is based on their physiological and / or behavioral. The postural control, despite that is a human behavioral characteristic, has not been well developed in the field of biometrics. The work performed in this thesis is based on the stabilometric signals analysis ant biometric application. Firstly, a study of the postural information especially the stabilometric signal is carried out through traditional analysis namely temporal, frequency and stochastic analysis and two decomposition methods named principle components analysis (ACP) decomposition and wavelet decomposition. The ACP method, based on the additive model, allows decomposing the signal into three components: a trend signal, a rambling signal and a trembling signal. The wavelet decomposition method allows decomposing the signal into three levels of detail signals and three signal levels of approximation. Through the study of postural stability, spectral analysis and phase analysis of the different components from the ACP and the wavelet decomposition, the comparison of these two methods concludes that the ACP method is more appropriate than the wavelet decomposition to analyze the stabilogram. From the decomposition methods and classical methods of analysis, several parameters are extracted to study the effect of different factors on postural stability and the center of mass displacement. These factors are named vision, direction, proprioception, age, gender, height and weight. A second aspect of this work is devoted to the application of biometrics, from the extracted parameters and through ANOVA statistic analysis, those that are most discriminative are used to identify subjects and classify them according to age, gender, weight and size. This biometric application is performed by three classification methods namely, K-NN, LDA and SVM. Biometric applications result in respectable recognition rate exceeding 80%. Therefore, it is inferred that the analysis of postural control is promising in the field of biometrics
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Besse, Apollos. "Modélisation mathématique de la leucémie myéloide chronique." Thesis, Lyon, 2017. http://www.theses.fr/2017LYSE1105/document.
Повний текст джерелаАнотація:
Cette thèse porte sur la dynamique de modèles de leucémie myéloïde chronique (LMC). Les modèles qui nous intéressent décrivent les populations de cellules leucémiques dans la moelle osseuse ou le sang, en compétition avec des populations de cellules saines ou avec le système immunitaire. Dans un premier chapitre, nous proposons une version mathématiquement analysable d'un modèle à équations différentielles ordinaires qui décrit l'interaction du système immunitaire avec les cellules leucémiques. Nous caractérisons l'existence d'équilibres et leur stabilité puis nous fournissons une analyse de bifurcation complète en co-dimension 1. Dans un deuxième chapitre, nous confrontons ce modèle à des données cliniques. Dans un troisième chapitre, nous proposons et analysons une version simplifiée d'un modèle d'équations aux dérivées partielles qui décrit la prolifération et la différenciation des cellules souches leucémiques dans la moelle osseuse et l'effet d'un traitement par ITK sur ces cellules. Nous nous intéressons au comportement à long terme des solutions, et à sa dépendance vis à vis du traitement. Dans un quatrième et dernier chapitre, nous nous intéressons à la stabilité des équations différentielles scalaires et autonomes à deux retards, qui apparaissent naturellement dans la modélisation de nombreux phénomènes biologiques ou physiques, comme la LMCThis thesis deals with the dynamics of models of chronic myeloid leukemia (CML). Models of interest describe leukemic cell populations in the bone marrow or in the blood, in competition with healthy cell populations or with the immune system. In a first chapter, we propose a mathematically tractable version of an ordinary differential equation model that describes the interaction of the immune system with leukemic cells. We characterize the existence of steady states and their stability and then we provide a complete bifurcation analysis in co-dimension 1. In a second chapter, we confront this model with clinical data. In a third chapter we propose and analyze a simplified version of a model of partial differential equations that describes the proliferation and differentiation of leukemic stem cells in the bone marrow and the effect of an TKI treatment on these cells. We are interested in the long-term behavior of the solutions, and its dependence on treatment. In a fourth and final chapter, we are interested in the stability of scalar and autonomous differential equations with two delays, which appear naturally in the modeling of many biological or physical phenomena, such as CML
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Jin, Chi. "Analyse de stabilité de systèmes à coefficients dépendant du retard." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLS411/document.
Повний текст джерелаАнотація:
Des systèmes avec des coefficients dépendant du retard ont été rencontrés dans diverses applications de la science et de l'ingénierie. Malgré la littérature abondante sur les systèmes de temporisation, il y a peu de résultats concernant l'analyse de stabilité des systèmes avec des coefficients dépendant du retard. Cette thèse est consacrée à l'analyse de stabilité de cette classe de systèmes.Les méthodes d'analyse de la stabilité sont développées à partir de l'équation caractéristique correspondante suivant une approche généralisée tau-décomposition. Étant donné un intervalle d'intérêt de retard, nous sommes capables d'identifier toutes les valeurs de retard critique contenues dans cet intervalle pour lesquelles l'équation caractéristique admet des racines sur l'axe imaginaire du plan complexe. Le critère de direction de croisement des racines sont proposées pour déterminer si ces racines caractéristique se déplacent vers le plan complexe demi-gauche ou demi-droite lorsque le paramètre de retard passe par ces valeurs de retard critique. Le nombre de racines caractéristiques instables pour un retard donné peut ainsi être déterminé. Notre analyse comprend les systèmes avec un seul retard ou des retards proportionnés sous certaines hypothèses. Le critère de direction de croisement des racines développés dans cette thèse peut être appliqués aux multiple racines caractéristiques, ou aux racines caractéristiques dont la position paramétrée par le retard est tangent à l'axe imaginaire. En tant qu'application, il est démontré que les systèmes avec des coefficients dépendant du retard peuvent provenir de schémas de contrôle qui utilisent une sortie retardée pour approcher ses dérivés pour la stabilisation. Les méthodes d'analyse de stabilité développées dans cette thèse sont adaptées et appliquées pour trouver les intervalles de retard qui atteignent un taux de convergence demandé du système en boucle ferméeSystems with delay-dependent coefficients have been encountered in various applications of science and engineering. However, general and systematic stability analysis is rarely reported in the rich literature on time-delay systems. This thesis is committed to the stability analysis of such class of systems.Stability analysis methods are developed based on the corresponding characteristic equation following a generalized tau-decomposition approach. Given a delay interval of interest, we are able to identify all the critical delay values contained in this interval for which the characteristic equation admits roots on the imaginary axis of the complex plane. Various root crossing direction criteria are proposed to determine whether these characteristic roots move toward the left or the right half complex plane as the delay parameter sweeps through these critical delay values. The number of unstable characteristic roots for any given delay can thus be determined. Our analysis covers systems with a single delay or commensurate delays under certain assumptions. The root crossing direction criteria developed in this thesis can be applied to characteristic roots with multiplicity, or characteristic roots whose locus parametrized by the delay is tangent to the imaginary axis. As an application, it is demonstrated that systems with delay-dependent coefficients can arise from control schemes that use delayed output to approximate its derivatives for stabilization. The stability analysis methods developed in this thesis are tailored and applied to find the delay intervals that achieve a demanded convergence rate of the closed-loop system
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Cochoy, Jérémy. "Decomposability and stability of multidimensional persistence." Thesis, Université Paris-Saclay (ComUE), 2018. http://www.theses.fr/2018SACLS566/document.
Повний текст джерелаАнотація:
Dans un contexte où des quantités toujours plus colossales de données sont disponibles,extraire des informations significatives et non triviales devient toujours plus difficile. Afin d’améliorer la classification, régression, ou encore l’analyse exploratoire de données, l’approche fournie par l’analyse topologique de données (TDA) est de rechercher la présence de formes dans le jeu de données.Dans cette thèse nous étudions les propriétés des modules de persistance multidimensionnelle dans le but d’obtenir une meilleure compréhension des sommandes et décompositions de ces derniers. Nous introduisons un foncteur qui plonge la catégorie des représentations de carquois dont le graphe est un arbre enraciné dans la catégorie des modules de persistance indexé sur ℝ². Nous enrichissons la structure de module de persistance provenant de l’application du foncteur cohomologie à une filtration en une structure d’algèbre de persistance.Enfin, nous généralisons l’approche de Crawley Beovey à la multipersistance et identifions une classe de modules de persistance indexé sur ℝ² qui possède des descripteurs simples et analogues au théorème de décomposition existant en persistance1-dimensionnelleIn a context where huge amounts of data are available, extracting meaningful and non trivial information is getting harder. In order to improve the tasks of classification, regression, or exploratory analysis, the approach provided by topological data analysisis to look for the presence of shapes in data set.In this thesis, we investigate the properties of multidimensional persistence modules in order to obtain a better understanding of the summands and decompositions of such modules. We introduce a functor that embeds the representations category of any quiver whose graph is a rooted tree into the category of ℝ²-indexed persistence modules. We also enrich the structure of persistence module arising from the cohomology of a filtration to a structure of persistence algebra.Finally, we generalize the approach of Crawley Beovey to multipersistence and identify a class of persistencemodules indexed on ℝ² which have simple descriptor and an analog of the decomposition theorem available in one dimensional persistence
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Lerisson, Gaétan. "Stabilité d'une onde de gravité interne, analyse locale, globale et croissance transitoire." Thesis, Université Paris-Saclay (ComUE), 2017. http://www.theses.fr/2017SACLX017/document.
Повний текст джерелаАнотація:
Dans les océans profonds linéairement stratifiés, la déstabilisation des ondes de gravité internes est importante car elle contribue probablement au mélange turbulent et à la circulation thermohaline.À l'aide de simulations numériques directes, nous créons un faisceau d'onde interne progressive. Cette situation est équivalente à une onde produite par l'oscillation de la marée sur une topographie sous-marine. Nous retrouvons les résultats expérimentaux obtenus par cite{Bourget13} : le faisceau se déstabilise en un mode petite échelle. Nous regardons l'effet d'un écoulement horizontal moyen sur cette instabilité en prenant soin d'abaisser la fréquence de forçage afin de compenser l'effet doppler et de conserver localement la même onde. Un cas limite apparaît lorsque le forçage devient stationnaire, ce qui équivaut à une onde de sillage issue d'un écoulement constant au dessus d'une topographie.Les écoulements à petite vitesse voient une instabilité petite échelle similaire au cas marée alors que les écoulement intermédiaires restent stables. Les écoulements plus rapides (jusqu'au cas sillage) voient, par contre, une instabilité bien plus grande échelle que celle dans le cas marée. Cette sélection d'échelle est robuste aux variations du nombre de Froude, de Reynolds, de la taille du faisceau ou de l'angle de l'onde.Nous montrons que ces instabilités peuvent être décrites comme des triades résonantes et que les différentes échelles correspondent à différentes branches triadiques. Nous confirmons la présence de cas stables pour des vitesses intermédiaires en calculant les modes propres comme des modes de Floquet à l'aide d'un algorithme d'Arnoldi--Krylov, et en montrant qu'ils sont associés à des taux de croissance négatifs.Le cas sillage est instable et nous le stabilisons par une méthode deselective frequency damping cite{Akervik06} afin d'obtenir un écoulement de base stationnaire autour duquel nous calculons les perturbations optimales qui maximisent l'énergie totale à différents horizons temporels. Pour des horizons courts, la perturbation optimale est petite échelle alors que pour des horizons longs, elle est grande échelle et converge vers la solution non-linéaire obtenue précédemment. Les horizons courts voient une instabilité triadique petite échelle advectée par l'écoulement et les horizons longs développent une instabilité d'une branche triadique grande échelle capable de se maintenir dans le faisceau malgré l'écoulement.Nous interprétons cette sélection de mode par le biais de la théorie des instabilités absolue ou convective. Dans le cas de l'onde de sillage l'instabilité grande échelle est absolue alors que la petite échelle est convective (et domine la croissance transitoire puisque son taux de croissance local est supérieur). Les rôles s'inversent dans le cas marée et l'instabilité petit échelle devient absolue alors que la grande échelle est convective. Nous confirmons cette hypothèse en calculant la réponse impulsionnelle d'une onde plane monochromatique dans un domaine 2Dpériodique. L'évolution spatio-temporelle d'une perturbation localisée en temps et en espace montre la formation de trois paquets d'onde, chacun étant associé à une branche triadique que nous identifions par une extension de la théorie triadique prenant en compte un désaccordage cite{McEwan77} et permettant de calculer la vitesse de groupe des sommets des paquets. En calculant ensuite le taux de croissance absolu le long de rayons à x/t et z/t constant, nous validons notre hypothèseInternal gravity waves that exist in a continuously stratified fluid are particularly important in the ocean. They transport energy and are thought to generate turbulent mixing, which contribute to the deep ocean circulation.We generate an internal wave beam that propagates in a continuously stratified fluid with direct numerical simulations. This situation is equivalent to a tidal wave, where the tidal flow oscillates over a topography and generates a wave. Experimental results obtained by cite{Bourget13} are recovered, ie. the beam destabilizes into a small scale mode. We consider the effect of an horizontal mean flow on the instability and lower the forcing frequency in order to compensate for the doppler effect and to keep locally the same wave. A limit case appears when the forcing becomes stationary. This case is equivalent to a lee wave appearing when a stratified fluid flows over a topography.For small mean flow, small scale instabilities develop as in the tidal case. The beam then stabilizes at intermediate mean flows and destabilizes again for increasing flow speed. At this second threshold, down to the lee wave case, the instability is of much larger scale than for the tidal case. Varying the Reynolds number, the Froude number, the wave angle or the beam size doesn't affect the instability scale selection : a small scale instability in the tidal regime, and large scale instability in the lee regime.We show that the instability mechanism may be interpreted using the triadic instability. Scale selection corresponds to different branches of triadic resonance. We confirm the presence of a stability region for intermediate value of the mean advection velocity by computing the linear eigenmode as Floquet mode with an Arnoldi-Krylov technique and show that the leading eigenmode has a negative growth rate.In the lee wave, case the flow is unstable and a selective frequency damping method cite{Akervik06} is used to compute a steady base flow. We then implement a linear direct-adjoint method to compute the optimal perturbations that maximizes the total energy at different time horizons. At short time horizon, the optimal perturbation is small scale while at large time the perturbation switches to a large scale solution and converges to the large scale mode observed through the nonlinear simulations. Short time transients correspond to the small scale triadic instability advected by the flow whereas the long time large scale instability corresponds to large scale branch of the triadic instability that is able to sustain the flow.We propose an interpretation of the selection of these different instabilities in term of absolute and convective instability. In the case of the lee wave, the large scale instability is absolute whereas the small scale instability is convective (and dominates the short time transient growth because it has a larger local growth rate). When the mean flow is varied, the properties of small scale and large scale instabilities exchange: in the tidal case the short scale instability is absolute and the large scale convective. This conjecture is confirmed by computing the impulse response around a plane monochromatic internal gravity wave in an extended two dimensional periodic domain. The spatio temporal evolution of a perturbation localized in space and time points out the formation of three different wave packets corresponding to different branches of triadic instability. Using the triadic theory with finite detuning cite{McEwan77},we derive the group velocity at the maximum growth rate of the three different branches of triadic instability and find a good agreement with the velocity of the three wave paquet maxima in the impulse response. Analyzing the impulse response along rays, i.e. at x/t and z/tconstant, we compute the absolute growth rate along all possible rays and validate our conjecture
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Cosson, Marjorie. "Stabilité du réseau électrique de distribution. Analyse du point de vue automatique d'un système complexe." Thesis, Université Paris-Saclay (ComUE), 2016. http://www.theses.fr/2016SACLC065/document.
Повний текст джерелаАнотація:
Pour maintenir la tension dans des bornes admissibles, des régulations locales de puissance réactive (Q) en fonction de la tension (U) sont envisagées sur les réseaux de distribution. Ces travaux étudient l’impact de ces régulations sur la stabilité des réseaux de distribution accueillant de la production. Une étude empirique confirme le risque d’instabilité de la tension et souligne le lien avec les paramètres de la régulation. Pour aider les gestionnaires à les choisir, trois méthodes d’étude de la stabilité sont proposées. Tout d’abord, une méthode formelle fondée sur les notions d’abstraction discrète et de bisimulation est développée. Elle offre une grande précision au prix d’un effort de calcul important. Pour contournercette difficulté, un critère analytique portant sur le temps de réponse des régulations Q(U) est formulé. Ensuite, un critère valable dans tous les cas est proposé pour les codes de réseaux. Enfin, l’extension desméthodes à des cas plus complexes est discutéeTo maintain the voltage within specified limits, local control laws of distributed generators (DGs) reactive power (Q) with respect to their voltage (U) have been considered. This work studies the impact of Q(U) control laws on distribution feeders’voltage stability. An empirical study confirms the risk of voltage instability and highlights its dependence on control law parameters. To help distribution grid operators to choose these parameters, three methods assessing stability are formulated.First, a formal method based on discrete abstraction and bisimulation calculation is developed. The proposed approach yields precise results but with a high computational load. Then, to overcome this issue, an analytical criterion adapting Q(U) control laws response time with respect to grid parameters is formulated. Finally, a general criterion, valid in any cases, is established in order to be included in the grid codes. To conclude this work, extension to more complex cases is discussed
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Hachemi, Fouad El. "Analyse de stabilité des systèmes à commutations singulièrement perturbés." Thesis, Université de Lorraine, 2012. http://www.theses.fr/2012LORR0229/document.
Повний текст джерелаАнотація:
Un grand nombre de phénomènes nous entourant peuvent être décrit par des modèles hybrides, c'est-à-dire, mettant en jeu simultanément une dynamique continu et une dynamique discrète. Également, il n'est pas rare que ces dynamiques puissent évoluer dans des échelles de temps différentes. Dans cette thèse, nous nous intéressons à l'analyse de stabilité des systèmes à commutations singulièrement perturbés à temps continu. En présence de commutations, l'analyse de stabilité des systèmes singulièrement perturbés dite "classique" (séparation des échelles de temps) n'est plus valable. En nous plaçant en dimension deux et en considérant deux modes, nous donnons une caractérisation complète du comportement asymptotique de tels systèmes lorsque le paramètre de perturbation tend vers zéro. Ensuite, nous étudions la discrétisation des systèmes à commutations singulièrement perturbés, en portant un intérêt particulier aux méthodes de discrétisation permettant de préserver la stabilité et les fonctions de Lyapunov quadratiques communesMany phenomena we encounter can be described by hybrid models, namely, consisting of one continuous dynamic and one discret dynamic at the same time. Moreover, these dynamics often evolves in different time scales. In this thesis, we deal with the stability analysis of singularly perturbed switched systems in continuous time. When we consider switchings, the "classical" approach (decoupling fast and slow dynamics) allowing to analyse stability of singularly perturbed systems doesn't hold anymore. Considering second order singularly perturbed switched systems woth two modes, we completely characterize de stability behavior of such systems when the perturbation parameter goes to zero. Then, we study the discretization of singularly perturbed switched systems. In particular, we focus on methods allowing to preserve stability and common quadratic Lyapunov functions
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Rigaud, Alexandre. "Analyse des notions de stabilité pour les modèles 2D de Roesser et de Fornasini-Marchesini." Thesis, Poitiers, 2022. http://www.theses.fr/2022POIT2307.
Повний текст джерелаАнотація:
Cette thèse présente les résultats de travaux sur lLes différentes notions de stabilité utilisées dans la littérature des systèmes dynamiques multidimensionnels. Plus précisément, dans le cadre des modèles 2D de Roesser et de Fornasini-Marchesini, nous analysons les notions de stabilité au sens de Lyapunov, stabilité asymptotique, stabilité(s) exponentielle(s) et stabilité structurelle, ainsi que les relations entre ces différentes propriétés. Le premier chapitre de ce mémoire effectue un certain nombre de rappels concernant les définitions de stabilité et les liens qui existent entre celles-ci, dans le but d'établir un cadre solide en vue d'étendre ces notions du cas 1D au cas 2D. Une fois ces rappels établis, nous présentons les modèles 2D que nous étudions. Le deuxième chapitre dresse la liste des définitions de stabilité utilisées pour les modèles 2D de Roesser et de Fornasini-Marchesini et établit les liens entre ces différentes définitions. Au cours du troisième chapitre, nous proposons une condition nécessaire et suffisante de stabilité asymptotique pour une certaine classe de modèles de Fornasini-Marchesini 2D discrets linéaires. Le quatrième et dernier chapitre propose une étude détaillée d'un modèle 1D non-linéaire qui possède la particularité rare d'être à la fois attractif et instable, et nous généralisons ce modèle particulier au cas 2D afin d'établir quelles propriétés se conservent ou non lorsque l'on passe du cas 1D au cas 2DThis thesis presents the results of research work on different notions of stability used in the literature of multidimensional dynamical systems. More precisely, within the framework of the 2D Roesser and Fornasini-Marchesini models, we analyze the notions of stability in the sense of Lyapunov, asymptotic stability, exponential stability(ies) and structural stability, as well as the relations between these different properties. The first chapter of this thesis carries out a certain number of reminders concerning the definitions of stability and the links which exist between them, with the aim of establishing a solid framework in order to extend these notions from the 1D case to the 2D case. Once these reminders have been established, we present the 2D models that we are studying. The second chapter lists the stability definitions used for the 2D Roesser and Fornasini-Marchesini models and establishes the links between these different definitions. In the third chapter, we propose a necessary and sufficient condition of asymptotic stability for a certain class of linear discrete 2D Fornasini-Marchesini models. The fourth and last chapter proposes a detailed study of a non-linear 1D model which has the rare characteristic of being both attractive and unstable, and we generalize this particular model to the 2D case in order to establish which properties are conserved. or not when passing from the 1D case to the 2D case
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Cherifi, Abdelmadjid. "Contribution à la commande des modèles Takagi-Sugeno : approche non-quadratique et synthèse D -stable." Thesis, Reims, 2017. http://www.theses.fr/2017REIMS016/document.
Повний текст джерелаАнотація:
Ce travail de thèse traite de l’analyse de la stabilité et la stabilisation des systèmes non-linéaires représentés par des modèles T-S. L’objectif est de réduire le conservatisme des conditions de stabilité, obtenue par la méthode directe de Lyapunov, et écrites, dans la mesure du possible, sous forme de LMIs. Dans ce cadre, deux contributions principales ont été apportées. Tout d’abord, nous avons proposé de nouvelles conditions de synthèse non-quadratique de lois de commande, strictement LMIs et sans restriction d’ordre, pour les modèles T-S via des FLICs. En effet, dans ce contexte, les résultats de la littérature ne sont valables que pour les modèles T-S d’ordre inférieur ou égal à 2. Afin de lever cette restriction, les conditions ont été obtenues grâce à la démonstration d’une propriété de dualité. Ensuite, peu de travaux traitant de la spécification des performances en boucle fermée, de nouvelles conditions LMIs (quadratiques et non-quadratiques) ont été proposées via le concept de D-stabilité. Dans un premier temps, la synthèse de lois de commande PDC et non-PDC D-stabilisantes a été proposée pour les modèles T-S nominaux. Ensuite, ces résultats ont été étendus au cas des modèles T-S incertains. De plus, nous avons mis en évidence, au travers d’un exemple de D-stabilisation en attitude d’un modèle de drone quadrirotor, que les modèles T-S incertains pouvaient être avantageusement considérés lorsque les non-linéarités d’un modèle non-linéaire dépendent à la fois de l’état et de l’entréeThis work deals with the stability analysis and the stabilisation of nonlinear systems represented by T-S models.The goal is to reduce the conservatism of the stability conditions, obtained through the direct Lyapunov methodand written, when it is possible, as LMIs. In this framework, two main contributions has been proposed. First ofall, we have proposed some new conditions based on FLICs, strictly LMIs and without any order restrictions, forthe non-quadratic design of control laws devoted to stabilize T-S models. Indeed, in this non-quadratic context,the existing works are only available for 2nd order T-S models. In order to unlock this restriction, the proposed conditions have been obtained based on the proof of a dual property. Then, starting from the fact that few worksdeals with the closed-loop performances specification, some new LMI conditions (quadratic and non-quadratic)have been proposed via the D-stability concept. As a first step, D-stabilizing PDC and non-PDC controller designhas been considered for nominal T-S models. Then, these results have been extended to uncertain T-S models.Moreover, it has been highlighted, from an example of the attitude D-stabilization of a quadrotor model, that wecan make use of uncertain T-S models to cope with nonlinear models involving nonlinearities depending on bothstate and input variables
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Moussavi, Said. "Analyse de la stabilité de la coupe d'un procédé d'usinage robotisé." Thesis, Clermont-Ferrand 2, 2016. http://www.theses.fr/2016CLF22697/document.
Повний текст джерелаАнотація:
La productivité des processus d'usinage robotisé est très souvent limitée par le manque de rigidité des robots et les problèmes vibratoires relatifs à l’instabilité de la coupe. L’analyse de l’instabilité de la coupe en usinage robotisé est un problème difficile en raison de la variabilité du comportement dynamique du robot dans son espace de travail. Par conséquent, le phénomène de broutement en usinage robotisé dépend non seulement des paramètres de coupe mais également de la configuration du robot. Le premier objectif de cette thèse est de déterminer une méthode de modélisation dynamique du robot, adaptée du point de vue de l’analyse des vibrations et de la stabilité en usinage robotisé. Cette approche a été réalisée sur le robot d’usinage industriel ABB IRB6660. Une démarche de recalage a été mise en place afin de déterminer les paramètres du modèle numérique du robot. Ensuite, une présentation 3D de la limite de stabilité en usinage robotisé prenant en compte les variations du comportement dynamique du robot est réalisée. Le deuxième objectif consiste à optimiser le procédé vis-à-vis de la stabilité de la coupe. Les variations du comportement dynamique du robot sont exploitées par la gestion des redondances fonctionnelles afin d’optimiser la configuration du robot du point de vue de la stabilité. L’analyse numérique a montré et les essais expérimentaux d’usinage ont confirmé la possibilité de passer de la zone instable à la zone stable par la gestion de la redondance fonctionnelle sans modifier les paramètres de coupeProductivity in robotic machining processes can be limited by the low rigidity of the overall structure and vibration instability (chatter). The robot’s dynamic behavior, due to changes in its posture along a machining trajectory, varies within its workspace. Chatter in robotic machining therefore depends not only on the cutting parameters but also on the robot configuration. The first objective of this thesis is to determine a dynamic modeling approach of the robot in order to analyze the vibration and the stability in robotic machining. This modeling approach has been realized to dynamic modeling of an ABB IRB6660 industrial robot. The numerical model parameters are adjusted on the basis of experimental modal identifications. Then, a three-dimensional representation of stability lobes diagram for the prediction to take into account the robot dynamic behavior variations in machining trajectory is established. The second objective is to optimize the robot configurations regarding stability. The dynamic behavior variations of the robot in the workspace are exploited through functional redundancy management in order to optimize robot configurations with respect to machining stability. The numerical analyze demonstrated and experimental machining tests confirmed that stability conditions in machining operations can be achieved by managing functional redundancy without changing the cutting parameters
Книги з теми "Stability analyse"
1
Como, Mario. Theory of stability of continuous elastic structures. Boca Raton: CRC, 1995.
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2
Valdés, Ernesto Garzón. Die Stabilität politischer Systeme: Analyse des Begriffs mit Fallbeispielen aus Lateinamerika. Freiburg [Breisgau]: K. Alber, 1988.
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3
Ökonomische Analyse von Naturrisiken am Beispiel von Hangrutschungen der Schwäbischen Alb. Köln: Geographische Institut der Universität zu Köln, 2010.
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Knöpfel, Carlo. Der Einfluss der politischen Stabilität auf die internationale Wettbewerbsfähigkeit der Schweiz: Kritische Analyse eines Standortfaktors. Grüsch: Rüegger, 1988.
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Thermostable proteins: Structural stability and design. Boca Raton, Fla: CRC Press, 2012.
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Hamaguchi, Kōzō. The protein molecule: Conformation, stability, and folding. Tokyo: Japan Scientific Societies Press, 1992.
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Belke, Ansgar. Politische Konjunkturzyklen in Theorie und Empirie: Eine kritische Analyse der Zeitreihendynamik in Partisan-Ansätzen. Tübingen: Mohr, 1996.
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Xu, Quanyun A. Stability-indicating HPLC methods for drug analysis. 3rd ed. Washington, D.C: American Pharmacists Association, 2008.
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Xu, Quanyun A. Stability-indicating HPLC methods for drug analysis. Washington, D.C: American Pharmaceutical Association, 1999.
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Ökonomische Analyse von Naturrisiken am Beispiel von Hangrutschungen der Schwäbischen Alb. Köln: Geograph. Inst. der Univ. zu Köln, 2010.
Знайти повний текст джерелаЧастини книг з теми "Stability analyse"
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Rahmouni, Walid, and Lahouaria Benasla. "Phase-Plane Methods to Analyse Power System Transient Stability." In Advanced Control Engineering Methods in Electrical Engineering Systems, 14–29. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-97816-1_2.
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von Wangenheim, Georg. "Central Stability or Unstable Decentralization? Why Enforcement is Unstable in Decentralized Governments." In Internationalisierung des Rechts und seine ökonomische Analyse, 691–704. Wiesbaden: Gabler, 2008. http://dx.doi.org/10.1007/978-3-8350-5582-7_51.
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Nevečeřalová, Nikol. "Role Evropského Stabilizačního Mechanismu v bankovní unii." In Interakce práva a ekonomie, 220–32. Brno: Masaryk University Press, 2021. http://dx.doi.org/10.5817/cz.muni.m210-9934-2021-13.
Повний текст джерелаАнотація:
This paper deals in detail with the issue of new role of the European Stabilization Mechanism and the relationship with the banking union, resp. to the Single Resolution Fund. Within the paper, the main attention is to focus on the ESM in relations to the Banking Union. The aim of the paper is in particular to analyse the named “funds”, whose primary objective is to ensure the stability of the Union.
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Bekka, N., M. Sellam, and A. Chpoun. "New Modified Pekkari Model to Analyse the Aeroelastic Stability Behaviour for a Flexible Overexpanded Rocket Nozzle." In 30th International Symposium on Shock Waves 1, 67–70. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-46213-4_10.
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Gitahi, Joseph, and Michael Hahn. "Evaluation of Crowd-Sourced PM2.5 Measurements from Low-Cost Sensors for Air Quality Mapping in Stuttgart City." In iCity. Transformative Research for the Livable, Intelligent, and Sustainable City, 225–40. Cham: Springer International Publishing, 2022. http://dx.doi.org/10.1007/978-3-030-92096-8_14.
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AbstractExposure to particulate matter (PM) pollution poses a major risk to the environment and human health. Monitoring PM pollution is thus crucial to understand particle distribution and mitigation. There has been rapid development of low-cost PM sensors and advancement in the field of Internet of Things (IoT) that has led to the deployment of the sensors by technology-aware people in cities. In this study, we evaluate the stability and accuracy of PM measurements from low-cost sensors crowd-sourced from a citizen science project in Stuttgart. Long-term measurements from the sensors show a strong correlation with measurements from reference stations with most of the selected sensors achieving Pearson correlation coefficients of r > 0.7. We investigate the stability of the sensors for reproducibility of measurements using five sensors installed at different height levels and horizontal distances. They exhibit minor variations with low correlation of variation (CV) values of between 10 and 14%. A CV of ≤10% is recommended for low-cost sensors. In a dense network, the sensors enable extraction pollution patterns and trends. We analyse PM measurements from 2 years using space-time pattern analysis and generate two clusters of sensors that have similar trends. The clustering shows the relationship between traffic and pollution with most sensors near major roads being in the same cluster.
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Menini, Laura, and Antonio Tornambè. "Stability Analysis." In Symmetries and Semi-invariants in the Analysis of Nonlinear Systems, 293–328. London: Springer London, 2011. http://dx.doi.org/10.1007/978-0-85729-612-2_8.
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Corriou, Jean-Pierre. "Stability Analysis." In Process Control, 117–42. Cham: Springer International Publishing, 2017. http://dx.doi.org/10.1007/978-3-319-61143-3_3.
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Corriou, Jean-Pierre. "Stability Analysis." In Process Control, 103–27. London: Springer London, 2004. http://dx.doi.org/10.1007/978-1-4471-3848-8_3.
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Boyadjiev, Christo. "Stability Analysis." In Theoretical Chemical Engineering, 297–401. Berlin, Heidelberg: Springer Berlin Heidelberg, 2010. http://dx.doi.org/10.1007/978-3-642-10778-8_6.
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Nagurney, Anna, and Ding Zhang. "Stability Analysis." In Projected Dynamical Systems and Variational Inequalities with Applications, 45–74. Boston, MA: Springer US, 1996. http://dx.doi.org/10.1007/978-1-4615-2301-7_3.
Повний текст джерелаТези доповідей конференцій з теми "Stability analyse"
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Zeitoun, Hammam O., Knut To̸rnes, John Li, Simon Wong, Ralph Brevet, and John Willcocks. "Advanced Dynamic Stability Analysis." In ASME 2009 28th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2009. http://dx.doi.org/10.1115/omae2009-79778.
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Several design approaches can be used to analyse the stability of subsea pipelines [1]. These design approaches vary in complexity and range between simple force-balance calculations to more comprehensive dynamic finite element simulations. The latter may be used to more accurately simulate the dynamic response of subsea pipelines exposed to waves and steady current kinematics, and can be applied to optimise pipeline stabilisation requirements. This paper describes the use of state-of-the-art transient dynamic finite elements analysis techniques to analyse pipeline dynamic response. The described techniques cover the various aspects of dynamic stability analysis, including: • Generation of hydrodynamic forces on subsea pipelines resulting from surface waves or internal waves. • Modelling of pipe-soil interaction. • Modelling of pipeline structural response. The paper discusses the advantages of using dynamic stability analysis for assessing the pipeline response, presents advanced analysis and modelling capabilities which have been applied and compares this to previously published knowledge. Further potential FE applications are also described which extends the applicability of the described model to analyse the pipeline response to a combined buckling and stability problem or to assess the dynamic response of a pipeline on a rough seabed.
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Dupertuis, M. A., R. R. E. Salomaa, and M. R. Siegrist. "Stability of Single-Mode Optically-Pumped Lasers." In Instabilities and Dynamics of Lasers and Nonlinear Optical Systems. Washington, D.C.: Optica Publishing Group, 1985. http://dx.doi.org/10.1364/idlnos.1985.wd9.
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Wang, Nan, Wei Li, and Enshun Ping. "A Analyse on the Virtual Simulation of Vehicle Stability." In 2010 International Conference on Measuring Technology and Mechatronics Automation (ICMTMA 2010). IEEE, 2010. http://dx.doi.org/10.1109/icmtma.2010.697.
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Wang Nan, Li Wei, and Ping Enshun. "A analyse on the virtual simulation of vehicle stability." In 2010 2nd International Asia Conference on Informatics in Control, Automation and Robotics (CAR 2010). IEEE, 2010. http://dx.doi.org/10.1109/car.2010.5456613.
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Shaobo Kang, Yaohua Luo, Jiang You, and Shijia Lv. "The input characteristic and stability analyse of inverter with induction motor." In 2011 International Conference on Information and Automation (ICIA). IEEE, 2011. http://dx.doi.org/10.1109/icinfa.2011.5949058.
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Luo, Yaohua, Shaobo Kang, Jiang You, and Bin Fu. "The input characteristic and stability analyse of power converter in distribution power systems." In 2010 International Conference on Information and Automation (ICIA). IEEE, 2010. http://dx.doi.org/10.1109/icinfa.2010.5512292.
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Bakken, Lars E., Erling Lunde, and Morten Løes. "Power Dip Impact on Compressor System Stability." In ASME Turbo Expo 2016: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/gt2016-56950.
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Knowledge of compressor system behaviour during a trip is essential to obtain reliable operation. Experience at a gas treatment plant has shown that the export compressors (43 MW) may enter the unstable area of the performance characteristics and suffer from surge and rotating stall in situations with voltage drops in the electricity grid. A detailed dynamic simulation model has been established to analyse the impact of different mechanical, process and control tuning aspects. The electric motor driven compressor, the protection valves and piping have been modelled and dynamic analyses performed to reveal the transient response. The main challenges are related to the compressor system/process design and to the compressor and variable speed drive (VSD) response during power dip or compressor trip. Based on experiences detailed sensitivity analyses have been performed, covering the impact of: compressor discharge volumes, performance characteristics — head rise to surge, dimensions of the recycle piping as well as the sizing, characteristics and trip signal delay of the recycle protection valve(s). This paper reports experience from analyses of the export compressor and driver behaviour during the first 3 seconds of an electric power/voltage dip. It is partly based on earlier tests and dynamic simulations performed for the facility, and partly on new technology challenges and opportunities. The main objective has been to study the compressor system sensitivity related to variation in available driver power during power dip and its impact on the transient rundown trajectory and recovery phase.
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Lerbet, Jean. "Stability of Singularities of a Kinematical Chain." In ASME 2005 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/detc2005-84126.
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Since few years, the geometry of singularities of kinematical chains is better known. Using both Lie group theory and concepts of differential or analytic geometry, we already classified these singularities according to the nature of the function f associated to the chain (f is a product of exponential mappings of a Lie group). In the most general case, the tangent cone at a singularity has been explicitely given. Here, a different (and more difficult) aspect of the problem is studied. The concrete realisation of a kinematical chain is never perfect. That means that the vectors of the Lie agebra defining the function f are not exactly those of the chain: they are deformed. What happens for the singularities in this case? Are they remaining or do they disappear during the deformation? First, the mechanical problem is analysed as this of the stability of the fuction f and mathematical tools concerning stable mappings are given. Stability of a mapping means that the orbit of f under the action of diffeomorphisms in the source and in the target is an open set and its infinitesimal equivalent formulation is noted the inf-stability. Then we prove that the set of singularities of first class itself is a sbmanifold and we analyse a condition of normal crossing of the restriction of f to its manifold of singularities. Applying a result of the general theory, the stability of f is analysed.
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Bubel, Julian, Christina Rudolph, and Ju¨rgen Grabe. "Stability of Temporary Submarine Slopes." In ASME 2011 30th International Conference on Ocean, Offshore and Arctic Engineering. ASMEDC, 2011. http://dx.doi.org/10.1115/omae2011-50157.
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Shallow foundation structures for offshore wind turbines offer ecological benefits compared to pile foundations as less noise is emitted at sea floor level during construction process. On the other hand, shallow offshore foundations can rarely be placed on top of the sea floor. Weak soils usually need to be excavated to place the foundation structure on more stable ground and thus, anthropogenic submarine slopes result. Steep but stable slopes meet both economic and ecologic aims as they minimise material movement and sediment disturbance. After Terzaghi [1] the angle β between slope and the horizontal of the ground surface of coarse-grained soil is at most equal to the critical state friction angle φc. However, it can be observed that natural submarine slopes of sandy soils are always much more shallow. Particularly fine-grained, cohesionless or almost cohesionless soils failed in the past, although the slope angle was much smaller than the critical state friction angle φc. Artificial (temporary) slopes do not appear and behave as natural submarine slopes, since the latter are already shaped by perpetual loads of waves, tide and mass movements. Physical simulations of different scales are used to analyse the stability of artificial submarine slopes with sandy soil of the North Sea. The study focuses on gravitational forces and impacts from the excavation processes. The simulations and theoretical considerations result in suggested slope angles for future shallow offshore foundations of wind farms in the North Sea.
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Gala´n-Vioque, J., M. A. Lago, and J. Valverde. "Stability and Bifurcations in a Model of a Follower Loaded Rod." In ASME 2011 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2011. http://dx.doi.org/10.1115/detc2011-47441.
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We analyse a continuous Cosserat model of a visco-elastic rod subjected to a combination of a conservative load and a follower term in one of the ends. The formalism takes into account the geometric non linearities that appear for large deformations from the straight solution. The resulting equation is a PDE whose solution can be analysed for special cases and the eigenvalues of the linearisation can be computed by a combination of numerical continuation and bifurcation results. We illustrate this method analysing the bifurcations of the straight solution of a rod subjected to a follower force. The dynamics and the bifurcation behaviour of the model are explored as the intensity of force is varied and as the mixture of conservative-follower terms varies continuously from the standard conservative case to the purely follower one. Special attention is paid to the corresponding transition from symmetry breaking pitchfork bifurcation (falling over mode) to the appearance of oscillations in a Hopf like bifurcation (if some material damping is included) or pure reversible Hamiltonian Hopf bifurcation in the absence of damping. After the onset of oscillations a complex dynamical behaviour frequently called flutter instability appears. The study is supplemented with the bifurcation analysis of the two elastically jointed follower pendula model as a simplified model of the continuous problem.
Звіти організацій з теми "Stability analyse"
1
Ulinskaitė, Jogilė, and Rosita Garškaitė-Antonowicz. The populist Far Right in Lithuania during Russia’s war against Ukraine. European Center for Populism Studies (ECPS), March 2023. http://dx.doi.org/10.55271/rp0024.
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In Lithuania, centrist populist parties have been challenging the stability of the party system since 2000. Yet Far Right populist parties have not yet managed to enter the parliament. As Russia’s war against Ukraine has unfolded, the Far Right has had to reorient itself in a changing political landscape. On the one hand, the economic and energy crisis resulting from the war seems to provide the perfect conditions for populist mobilization in a low-trust and low-participation society. On the other, the Lithuanian government has benefited from a rally-around-the-flag effect. Lithuanian society has been particularly active in supporting Kyiv and welcoming refugees from Ukraine. In this article, we analyse the rhetoric of the Lithuanian populist Far Right, focusing on how these parties position themselves in light of changing circumstances due to the war and how they reframe criticism of national and international elites.
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Walshire, Lucas, Joseph Dunbar, and Benjamin Breland. Stability analysis of Old River Low Sill Structure. Engineer Research and Development Center (U.S.), September 2022. http://dx.doi.org/10.21079/11681/45349.
Повний текст джерелаАнотація:
An updated stability analysis was performed on the Old River Low Sill Structure due to a change in the operating conditions from historic river sedimentation. Sedimentation of the Mississippi River channel since the 1973 spring flood has caused higher river stages at lower discharges. Numerical methods used included nonlinear analysis of pile group stability, seepage analyses, and limit equilibrium methods. The structure’s foundation was compromised during the 1973 flood, and emergency repairs were conducted to prevent scouring and undermining of the foundation by the flood scour. Rehabilitation included the reconstruction of a failed wing wall on the left abutment, rock and riprap fill in the forebay channel, and emergency grouting to fill the scour hole beneath the structure. An operating restriction was emplaced to limit the differential head across the structure due to flood damage. Taking these conditions into account, results from an updated analysis showed that full headwater uplift caused increased tension in the piles, while the increased body load caused increased compressive loads in the piles. Review of piezometric monitoring and the seepage analyses showed that full headwater uplift is unlikely, indicating the foundation grouting adequately sealed the scour hole beneath the structure. Analysis results exhibited lower magnitude compression and tension loads in the piles with design load cases compared to previous analyses. Recommendations from these analyses indicate that increased monitoring and additional investigation may support increasing the differential head limitation.
3
Hughes, M. H., M. W. Phillps, A. M. M. Todd, J. Krishnaswami, and R. Hartley. High beta and second stability region transport and stability analysis. Office of Scientific and Technical Information (OSTI), September 1992. http://dx.doi.org/10.2172/7192576.
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4
Author, Not Given. High beta and second stability region transport and stability analysis. Office of Scientific and Technical Information (OSTI), September 1991. http://dx.doi.org/10.2172/5125728.
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5
Author, Not Given. High beta and second stability region transport and stability analysis. Office of Scientific and Technical Information (OSTI), June 1990. http://dx.doi.org/10.2172/6225021.
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6
Riley, W. J., and W. J. Riley. Handbook of frequency stability analysis. Gaithersburg, MD: National Institute of Standards and Technology, 2008. http://dx.doi.org/10.6028/nist.sp.1065.
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7
Ferrier, Bernard, and John Duncan. UAV Deck Recovery Stability Analysis. Fort Belvoir, VA: Defense Technical Information Center, January 2012. http://dx.doi.org/10.21236/ada557352.
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8
Hughes, M. H., M. W. Phillps, A. M. M. Todd, J. Krishnaswami, and R. Hartley. High beta and second stability region transport and stability analysis. Final report. Office of Scientific and Technical Information (OSTI), September 1992. http://dx.doi.org/10.2172/10183308.
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9
Hughes, M. H., and M. W. Phillips. High beta and second stability region transport and stability analysis. Final report. Office of Scientific and Technical Information (OSTI), January 1996. http://dx.doi.org/10.2172/661600.
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10
Wagnild, Ross Martin. Stability Analysis of HEG Shot 1443. Office of Scientific and Technical Information (OSTI), September 2014. http://dx.doi.org/10.2172/1171582.
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